1. Field of the Invention
The present disclosure relates to a liquid crystal display (“LCD”) device and a method of manufacturing the same and, more particularly, to an amorphous silicon thin film transistor-liquid crystal display device (“TFT-LCD”) in which a gate driving circuit is integrated on an amorphous silicon thin film transistor (“TFT”) substrate, and a method of manufacturing the same.
2. Description of the Related Art
In this information age, electronic display devices are becoming more important as information transmission media and various electronic display devices are widely applied in industrial apparatus and home appliances. Such electronic display devices are being continuously improved to have new functions appropriate for the various demands of an information society.
In general, electronic display devices display and transmit various pieces of information to users who utilize such information. That is, the electronic display devices convert electric information signals output from electronic apparatus into light information signals recognized by users through their eyes.
Electronic display devices may be categorized into emissive display device types and non-emissive display device types, where an emissive display device displays light information signals through a light emission phenomena thereof and a non-emissive display device displays the light information signals through a reflection, a scattering or an interference thereof. The emissive display device type may include a cathode ray tube (“CRT”), a plasma display panel (“PDP”), a light emitting diode (“LED”) and/or an electroluminescent display (“ELD”), for example. Emissive display devices are also called active display devices.
The non-emissive display devices, which are also called passive display devices, may include a liquid crystal display (“LCD”), an electrochemical display (“ECD”) and/or an electrophoretic image display (“EPID”), for example.
The CRT has been typically used as a television receiver display and as a monitor for a computer. The CRT has already been used for a long time since it generally has a relatively high quality and a low manufacturing cost. The CRT, however, has some disadvantages such as, for example, a heavy weight, a large volume and a high power dissipation.
Recently, the demand for improved electronic display devices has led to great interest in devices such as flat panel displays, which can offer excellent characteristics including thin thickness, light weight, low driving voltage and low power consumption. Such flat panel display devices may be manufactured according to improved semiconductor technologies.
In the flat panel devices, a liquid crystal display (“LCD”) device has been widely utilized for various electronic devices because the LCD device offers a thin thickness and a low power dissipation while maintaining a relatively high display quality approximately equal to that of a CRT. In addition, the LCD device can be operated under a low driving voltage, and can be easily manufactured such that the LCD device is widely used for various electronic apparatuses.
The LCD typically comprises two substrates, each of the substrates having an electrode, with a liquid crystal layer interposed therebetween. In the LCD, a voltage is applied across the electrodes to realign liquid crystal molecules and control an amount of light transmitted through the molecules.
With typical LCDs, the device typically includes electrodes formed on each of two substrates and a thin film transistor for switching a voltage applied to each of the electrodes. Generally, the thin film transistor is formed on one of the two substrates.
The LCD device types utilizing the thin film transistor in a pixel region may be divided into an amorphous silicon type TFT-LCD and a polycrystalline silicon type TFT-LCD. The polycrystalline silicon TFT-LCD device has a relatively low power consumption and cost, but the polycrystalline silicon type TFT-LCD manufacturing process is complicated compared to that of the amorphous silicon type TFT-LCD device. Accordingly, the polycrystalline silicon TFT-LCD is mainly used for small-sized displays such as, for example, mobile telephones. The amorphous silicon TFT-LCD is suitable for a large-sized displays and has a high yield, so it is used for displays having a large screen such as, for example, a notebook personal computer (“PC”), an LCD monitor, a high definition television (“HDTV”) receiver monitor, and the like.
As shown in FIG. 1 for a typical polycrystalline silicon TFT-LCD device, a data driving circuit 12 and a gate driving circuit 14 are formed on a glass substrate 10 on which pixel arrays are formed. A terminal 16 is connected to an integrated printed circuit board (“PCB”) 20 through a film cable 18. This structure can reduce manufacturing costs and minimize the power loss by integrating the driving circuits.
As shown in FIG. 2 for a typical amorphous silicon TFT-LCD device, a data driving chip 34 is formed on a flexible PCB 32 by a chip on film (“COF”) method and a data PCB 36 is connected to a data line terminal of pixel array through the flexible PCB 32. Further, a gate driving chip 40 is formed on a flexible PCB 38 by the COF method, and a gate PCB 42 is connected to a gate line terminal of pixel array through the flexible PCB 38.
A recently suggested method is an integrated PCB technology wherein a gate power supply is mounted on a data PCB to thereby eliminate a gate PCB. Korea Patent Laid-Open Publication Number 2000-66493 disclosed an LCD module adopting an integrated PCB from which the gate PCB is removed.
However, even if the integrated PCB is adopted, a flexible PCB on which a gate driving circuit is formed is still used. Accordingly, since a process of assembling a plurality of flexible PCBs on a glass substrate is carried out in the manufacture of amorphous silicon TFT-LCD devices, an outer lead bonding (“OLB”) process is more complicated as compared to the polycrystalline silicon TFT-LCD, thereby raising the manufacturing cost.